Luke 12:51

“Do you think that I am come to give peace in the earth? I tell you, No, but rather division.”

Having spoken of the fire that He is casting on the earth He now stresses what its result will be, that rather than His coming and His suffering as the Messiah uniting the people of Israel and leading them into a period of peace and plenty, (while they simply stood by and waited, which is what they were expecting), it will rather disturb and divide them, causing harsh divisions between them, a situation brought out quite clearly in the Book of Acts where there is continual division caused by the preaching of the word. His truth is open to all, but because it will only be received by the few (although often called ‘many' e.g. Mark 10:45) and will be rejected by the majority it will cause dissension and disagreement.